This disclosure concerns an invention relating generally to shock-absorbing devices for snowplows, and more specifically to shock-absorbing devices for assemblies which mount snowplow moldboards to their plowing vehicles.
Most moldboards for snowplows are affixed to their plowing vehicles by an assembly which will be referred to herein as a vehicle mount, which may take a variety of forms. Often, the vehicle mount includes a mounting frame which is permanently or removably attached to the plowing vehicle. A support frame, which is often provided as a truss-like structure commonly referred to as an A-frame, bears the moldboard and removably attaches to the mounting frame so that the support frame (and its associated moldboard) can be removed from the vehicle. The moldboard is often pivotally affixed to the support frame (and more generally to the vehicle mount) by an assembly referred to as a reversing table so that the reversing table and moldboard may rotate in one or more degrees of freedom with respect to the vehicle mount, e.g., in a horizontal plane so that the moldboard can be reoriented from one side of the plowing vehicle to the other. The moldboard may also be pivotally connected to the reversing table (or to the vehicle mount) so that the moldboard may rotate about a horizontal axis to enable the moldboard to be raised and lowered. Reference can be made to U.S. Pat. No. 4,976,054 to Jones, and to the patents referenced therein, for illustrations of a variety of reversing table and vehicle mount arrangements. The moldboard may include a lower trip edge, i.e., a spring-loaded lower plowing edge, which yields under impact to avoid damage to the moldboard; see, e.g., U.S. Pat. No. 5,437,113 to Jones and the patents referenced therein.
The foregoing assembly is subjected to a great deal of wear owing to road vibration and impact loading, and since failure can lead to significant cost and inconvenience, plow manufacturers strive to develop means for minimizing wear. In particular, the pivots at which the moldboard rotates with respect to the reversing table, and the connections by which the reversing table rotates with respect to the vehicle mount, are subject to problems because these are generally the first points at which the assembly will fail. Thus far, the solution for such failure has generally been to fortify the structure of the vehicle mount, reversing table, and moldboard at these points. This has the disadvantages that it increases the weight and cost of the assembly, and complicates repairs when such are finally needed.
The invention, which is defined by the claims set forth at the end of this document, is directed to shock-absorbing devices for plows which at least partially alleviate the aforementioned problems. A basic understanding of some of the preferred features of the invention can be attained from a review of the following brief summary of the invention, with more details being provided elsewhere in this document.
Plows made in accordance with the invention preferably include at least one of the following features:
(1) The plow moldboard is affixed to a plow reversing table at one or more pivots which allow the moldboard to be rotatably repositioned with respect to the reversing table. One of the moldboard or the reversing table includes a bearing thereon, with the bearing having a bearing bore defined therein. The other of the moldboard or the reversing table includes a pin which is elastically journalled within the bearing bore so that the pin and bearing may rotate with respect to each other, and additionally translate with respect to each other in radial directions (i.e., in planes which are generally parallel to the axes of the pin and the bearing bore). Therefore, the pin will translate within the bearing when the moldboard is subjected to loading. Such translation will help to delay triggering of any trip edge situated on the moldboard, and will thereby help avoid the shock that occurs from such triggering and allow the pivots to avoid breakage. The elastic journalling may be accomplished by interposing a bushing between the bearing and the pin wherein the bushing is at least partially elastic. The bushing preferably includes a rigid inner sleeve wherein the pin is received, and an elastic outer sleeve wherein the inner sleeve is situated. The inner sleeve and outer sleeve are preferably bonded together so as to prevent the two from separating under loading, which can promote wear between the inner and outer sleeves.
(2) The reversing table is rotatably affixed to the vehicle mount with a linear actuator affixed therebetween so that actuation of the linear actuator will cause the reversing table to rotate with respect to the vehicle mount. The linear actuator is elastically mounted between the reversing table and vehicle mount so that the two may rotate a slight amount with respect to each other (with such rotation being elastically resisted), and so that shock loading of the moldboard (and thus the reversing table) will not be readily transmitted to the linear actuator. The linear actuator is preferably mounted to at least one of the vehicle mount and the reversing table by an actuator anchor wherein an elastic cushion is fit between the linear actuator and actuator anchor. The actuator anchor may have a mounting bore in which the linear actuator is slidably fit, and an elastic cushion may be fit about the linear actuator and closely between the linear actuator and actuator anchor. Then, when the linear actuator translates within the mounting bore of the actuator anchor, the elastic cushion will be compressed or expanded by a corresponding amount.
Further advantages, features, and objects of the invention will be apparent from the following detailed description of the invention in conjunction with the associated drawings.